1. Field of the Invention
This invention is related to the detection of analytes in industrial water systems with cyanine dyes.
2. Description of Related Art
Water is used in a number of industrial water systems such as cooling and boiler water systems. Municipal or untreated water contain substances which can affect heat transfer, fluid flow or cause corrosion of system equipment. The presence of these substances and any resulted scaling, biofouling and corrosion adversely affects the rate of heat transfer, and therefore the efficiency of the system. Accordingly, before the water is utilized for cooling or steam purposes, it is desirably treated with appropriate chemicals.
Chemical treatment of water is well developed and widely used. For example, it is known to add polyelectrolytes to the water to reduce scaling. One particularly useful polyelectrolyte is Coag139D (PMA, polymethacrylic acid); although other polyelectrolytes such as AEC (alcohol ether carboxylates), APES (alkylphenol ethoxylates) and HPS-I (hydroxypropyl sulfonate ether copolymers) are in use as well. However, the employment of polyelectrolytes in industrial water systems presents its own set of problems because the concentration of the polyelectrolytes in the water must be carefully monitored. For example, if too little of the polyelectrolytes is employed, scaling will occur. In contrast, if too high a concentration of the polyelectrolytes is employed, then the cost/performance efficiency of the system is adversely affected. As with other methods of chemically treating aqueous systems, there is an optimal concentration of treatment chemicals that should be maintained.
Several methods for determining the concentration of polyelectrolytes in aqueous systems are available. For example, there are several colorimetric methods for determination of polyelectrolytes using dyes. One example is U.S. Pat. No. 6,214,627 issued to Ciota et al, herein incorporated by reference. In addition, there is a Hach polyacrylic acid method that uses iron thiocyanate chelation to detect calibration based on polyacrylic acid. Generally, these methods require a complicated, multi-step operation procedure and are difficult to carry out in the field. Other methods, such as the one disclosed in U.S. Pat. No. 5,958,778 issued to Johnson et al., herein incorporated by reference, use luminol-tagged polymers in combination with fluorescent or chemiluminescent detection techniques to monitor the industrial waters. Also, there is a turbidity method that relies on the formation of insoluble compounds for determining the concentration of water-soluble polymers. This method is lengthy and is susceptible to inaccuracies.
Thus, there exists a strong need for simplified test methods that can easily be used to determine the concentration of analytes in industrial water sources.